Good job there Shure!
It's nice to see finally some Quad driver IEM based on other drivers than DTEC+TWFK Combo. Don't get me wrong Westone 4 or Heir 4 or UE900 sound great but with the shure's design you can get one step further IMHO.
Low impedance seems to be an effect of a very low tweeter cutting (lower than 1kHz). However it doesn't mean earphones will be picky for source, because we are talking about 1kHz impedance... balanced armatures are highly inductive which means there can be even 30 Ohm difference between say 1kHz and 3kHz. The bass drivers have higher impedance @20 or 200Hz than 9 Ohm, believe me.
[Edit] I just noticed that each driver has frequency range marked on it :) tweeter is cut at 2kHz, plus the wiring is solid core!
Edited by piotrus-g - 5/9/13 at 1:51am